Glaucoma is a group of ocular diseases which is believed to develop as a result of an increase in ocular pressure that pinches the optic nerve at the back of the retina, and affects tens of millions of people worldwide. Those affected by glaucoma may experience gradual loss in their peripheral vision. Glaucoma has been nicknamed the “silent thief of sight” because the loss of vision occurs gradually over a long period of time and is often only recognized when the disease is quite advanced. Once the visual field is lost, the damage cannot be recovered. Moreover, lab-on-a-chip (LOC) technology pertains to a device that integrates one or more laboratory functions on a single chip of only millimeters to a few square centimeters in size and pertains to the handling of extremely small fluid volumes down to a less than pico litters. LOC field more and more exceeds the borders between lithography-based microsystem technology, nano technology and precision engineering for added system value and is believed to become an important part of the efforts to improve global health through the development of point-of-care testing devices.
As we move into the world of distributed, ubiquitous computing, sensors will play an increasing role in interfacing between the digital world and the real world. Specifically for glaucoma diagnosis, a low-cost, unpowered wireless sensor which can immediately detect changes in intraocular pressure is in great demand for rapid, point-of-care diagnosis, since early detection can quickly prevent irreversible damage to human vision. In even higher demand is a sensor which can be directly integrated with existing wireless infrastructure.
Prior art in the development of wireless pressure sensor have employed inductor-capacitor coupling techniques, microfabricated strain gauges, complementary metal oxide semiconductor (CMOS) based technologies and other radio frequency powered which often employ nonbiocompatible metals, complicated manufacturing processing and materials. To the best of the inventors' knowledge, no unpowered, wireless pressure sensor which employs a microfluidic network to relate pressure to a corresponding fluidic displacement which can be consequently readout through an optical imaging system has been disclosed.